1. Field of the Invention
The present invention relates to recording apparatuses and recording methods, and particularly, to a technology for correcting a conveyance error of a recording medium.
2. Description of the Related Art
When a recording medium is being conveyed in an inkjet recording apparatus (recording apparatus), the recording medium may come into contact with a recording head due to lifting or sagging of the recording medium, possibly resulting in contamination of or damages to the recording head. In order to solve such a problem, Japanese Patent Laid-Open No. 2005-194043 discloses a technology in which the peripheral speed of a conveying roller disposed upstream in the conveying direction is set higher than that of an eject roller disposed downstream and configured to convey the recording medium.
When the peripheral speed of the conveying roller is set higher than that of the eject roller, the recording medium is conveyed excessively by an amount greater than a predetermined conveying amount when the trailing end of the recording medium disengages from a nip portion of the conveying roller. This can possibly lower the image quality significantly. In light of this, for the purpose of achieving a stable conveying operation, the peripheral speed of the conveying roller is set equal to that of the eject roller, that is, the peripheral-speed ratio between the conveying roller and the eject roller is set to “1”, at the timing at which the trailing end of the recording medium disengages from the nip portion of the conveying roller.
As a result of many analyses by the present inventors, the present inventors have discovered that the peripheral-speed ratio between the conveying roller and the eject roller is significantly affected by eccentricity of the rollers. The term “eccentricity of the rollers” refers to a state where a roller does not have the shape of a perfect circle in cross section and the center of rotation of the roller is thus shifted. When there is eccentricity in a roller, the length thereof in the circumferential direction (arc length) and the peripheral speed thereof undesirably fluctuate according to the rotational position (rotational phase) of the roller.